Efficacy of magnetic capture in comparison with conventional DNA isolation in a survey of Toxoplasma gondii in wild house mice

Prevalence of Toxoplasma gondii in Endangered Wild Felines (Felis silvestris and Lynx pardinus) in Spain

The wildcat (Felis silvestris) and the Iberian lynx (Lynx pardinus) are important species in Spain, considered as near-threatened and endangered, respectively. Both can be infected by Toxoplasma gondii, a parasite that can cause morbidity and mortality in transplacentally-infected or immunocompromised mammals. The data on the prevalence of this parasite in wild populations of these species in Spain are outdated. The objective of this study was to update information and evaluate the role of these felines in parasite epidemiology and the potential impact of the parasite on their conservation. Blood and fecal samples were collected from captured animals, as well as the tongue, diaphragm, and spleen, from animals killed in road accidents in central Spain. An indirect fluorescent antibody test (IFAT) was used to detect parasite antibodies in serum, microscopy and molecular analysis were used to detect oocysts in feces, and molecular analysis was used to determine the existence of tissue cysts. Seroprevalence was 85% in wildcats and 45% in lynx, and parasite DNA was detected in the feces of one wildcat and in tissue samples from 10 wildcats and 11 Iberian lynxes. These results highlight the epidemiological importance and high risk of T. gondii infection in animals and humans in the studied areas. Considering feline susceptibility to infection, monitoring programs are needed to assess the health status of wild felines.

Inactivation of Toxoplasma gondii in dry sausage and processed pork, and quantification of the pathogen in pig tissues prior to production

Toxoplasma gondii is an important zoonotic foodborne parasite. Meat of infected animals appears to be a major source of infection in Europe. Pork is the most consumed meat in France, with dry sausages well represented. The risk of transmission via consumption of processed pork products is largely unknown, mainly since processing will affect viability but may not entirely inactivate all T. gondii parasites. We investigated the presence and concentration of T. gondii DNA in the shoulder, breast, ham, and heart of pigs orally inoculated with 1000 oocysts (n = 3) or tissue cysts (n = 3) and naturally infected pigs (n = 2), by means of magnetic capture qPCR (MC-qPCR). Muscle tissues of experimentally infected pigs were further used to evaluate the impact of manufacturing processes of dry sausages, including different concentrations of nitrates (0, 60, 120, 200 ppm), nitrites (0, 60, 120 ppm), and NaCl (0, 20, 26 g/kg), ripening (2 days at 16-24 °C) and drying (up to 30 days at 13 °C), by a combination of mouse bioassay, qPCR and MC-qPCR. DNA of T. gondii was detected in all eight pigs, including in 41.7% (10/24) of muscle samples (shoulder, breast and ham) and 87.5% (7/8) of hearts by MC-qPCR. The number of parasites per gram of tissue was estimated to be the lowest in the hams (arithmetic mean (M) = 1, standard deviation (SD) = 2) and the highest in the hearts (M = 147, SD = 233). However, the T. gondii burden estimates varied on the individual animal level, the tissue tested and the parasitic stage used for the experimental infection (oocysts or tissue cysts). Of dry sausages and processed pork, 94.4% (51/54) were positive for T. gondii by MC-qPCR or qPCR, with the mean T. gondii burden estimate equivalent to 31 parasites per gram (SD = 93). Only the untreated processed pork sample collected on the day of production was positive by mouse bioassay. The results suggest an uneven distribution of T. gondii in the tissues examined, and possibly an absence or a concentration below the detection limit in some of them. Moreover, the processing of dry sausages and processed pork with NaCl, nitrates, and nitrites has an impact on the viability of T. gondii from the first day of production. Results are valuable input for future risk assessments aiming to estimate the relative contribution of different sources of T. gondii human infections.

Direct detection and quantification of Toxoplasma gondii in meat samples from feral raccoons (Procyon lotor) in Germany by magnetic-capture real-time PCR

Because the number of wild raccoons in Germany is increasing constantly, it appears to be economic reasonable to use their meat as food. For this purpose, it is essential to generate data regarding the pathogen load of the meat to be consumed and handled. It is known that raccoons, particularly in Germany, show a high seroprevalence of Toxoplasma gondii. Because serological data only indicates contact of a host to a parasite additional direct detection is needed to prove presence of parasitic stages in particular tissues. Therefore, a total of 150 samples from raccoons with known serostatus were tested and quantified using magnetic-capture real-time PCR for Toxoplasma gondii. As it represents potentially consumption-relevant parts of raccoons, meat from forelimb and hindlimb was examined. Samples were stratified into three groups based on the animals' serostatus (each 50 negative, low positive, and high positive). All samples from seronegative animals were found negative by MC-PCR as well. In a total of 56 meat samples from 100 seropositive animals, T. gondii DNA was detected. Statistically significant more samples were positive by MC-PCR in the high positive than in the low positive serostatus group (38/50 vs. 18/50, p < 0.0001). Furthermore, samples from the former group were also found to have statistically significant higher DNA equivalent values compared to samples from the low positive serostatus group (p < 0.0001). These results suggest that meat from seropositive raccoons may contain considerable numbers of T. gondii presenting a potential public health risk for humans whilst handling and consumption.

Towards an Integrated Approach for Monitoring Toxoplasmosis in Southern Italy

Simple Summary

Toxoplasmosis is a significant public health issue worldwide, caused by the intracellular protozoan Toxoplasma gondii. It has a heteroxenous life cycle in which felines act as definitive reservoirs and a wide range of warm-blooded animals, including humans, act as intermediate hosts. Due to the complex life cycle, monitoring, prevention and control of this parasite are very difficult. A thorough analysis of the epidemiology of T. gondii in humans, animals and food as well as the risk factors associated with the infection are needed to plan adequate control strategies in a given geographical area. Based on this, an integrated approach for monitoring toxoplasmosis was developed and conducted in an endemic area of southern Italy. The main tasks of this approach were based on the following strategies: parasitological and risk factor analysis for T. gondii in livestock farms, serological and molecular monitoring in meat-producing livestock at slaughterhouses, hospital discharge records (HDRs) analysis and outreach activities. The findings of this study confirmed the spread of T. gondii infection in southern Italy with high prevalence values in ruminants and the need of valid control strategies based on comprehensive and transdisciplinary actions according to the One Health approach.

Abstract

Toxoplasmosis is a widespread worldwide zoonotic infection caused by the intracellular protozoan Toxoplasma gondii. This protozoan infection is considered one of the most important food-borne parasitic zoonoses globally. Beyond its impact on public health, toxoplasmosis has also important veterinary implications, because it causes miscarriage or congenital malformations in livestock with negative economic impacts. An integrated monitoring programme aimed to deepen the epidemiological data on toxoplasmosis and to identify the risk factors that may favour T. gondii infections in animals and humans was conducted in an endemic area of southern Italy. The monitoring activities were based on the following tasks: (i) parasitological analysis and risk factors for T. gondii in livestock (sheep, goat, cattle and water buffalo) farms; (ii) serological and molecular monitoring at slaughterhouse in meat-producing livestock; (iii) analysis of hospital discharge records (HDRs); (iv) outreach activities (information, dissemination and health education) to farmers, vet practitioners and school-age children. The present study confirmed a very high seroprevalence of T. gondii infection in livestock farms (e.g., up to 93.1% in sheep farms) in southern Italy and highlighted the potentially significant public health risk in this area.

Epidemiological Significance of Toxoplasma Gondii Infections in Wild Rodents: 2009-2020

Toxoplasma gondii infections are common in humans and animals worldwide. Rodents are one of the most important intermediate hosts for T. gondii because they are preyed on by cats, who in turn excrete the environmentally resistant oocysts in their feces and thus spread the infection. Information on T. gondii infections is spread in numerous reports and is not easily accessible to readers. Here, we review prevalence, persistence of infection, clinical disease, epidemiology, and genetic diversity of T. gondii infections in wild rodents worldwide. Data are tabulated by country, by each rodent species alphabetically, and chronologically. Recent genetic diversity of T. gondii strains in rodents is critically evaluated.

Serological and molecular detection of Toxoplasma gondii in terrestrial and marine wildlife harvested for food in Nunavik, Canada

BACKGROUND

Toxoplasma gondii, a zoonotic protozoan parasite, infects mammals and birds worldwide. Infection in humans is often asymptomatic, though illnesses can occur in immunocompromised hosts and the fetuses of susceptible women infected during pregnancy. In Nunavik, Canada, 60% of the Inuit population has measurable antibodies against T. gondii. Handling and consumption of wildlife have been identified as risk factors for exposure. Serological evidence of exposure has been reported for wildlife in Nunavik; however, T. gondii has not been detected in wildlife tissues commonly consumed by Inuit.

METHODS

We used a magnetic capture DNA extraction and real-time PCR protocol to extract and amplify T. gondii DNA from large quantities of tissues (up to 100 g) of 441 individual animals in Nunavik: 166 ptarmigan (Lagopus lagopus), 156 geese (Branta canadensis and Chen caerulescens), 61 ringed seals (Pusa hispida), 31 caribou (Rangifer tarandus) and 27 walruses (Odobenus rosmarus).

RESULTS

DNA from T. gondii was detected in 9% (95% CI: 3-15%) of geese from four communities in western and southern Nunavik, but DNA was not detected in other wildlife species including 20% (95% CI: 12-31%) of ringed seals and 26% (95% CI: 14-43%) of caribou positive on a commercial modified agglutination test (MAT) using thawed heart muscle juice. In geese, tissue parasite burden was highest in heart, followed by brain, breast muscle, liver and gizzard. Serological results did not correlate well with tissue infection status for any wildlife species.

CONCLUSIONS

To our knowledge, this is the first report on the detection, quantification, and characterization of DNA of T. gondii (clonal lineage II in one goose) from wildlife harvested for food in Nunavik, which supports the hypothesis that migratory geese can carry T. gondii into Nunavik where feline definitive hosts are rare. This study suggests that direct detection methods may be useful for detection of T. gondii in wildlife harvested for human consumption and provides data needed for a quantitative exposure assessment that will determine the risk of T. gondii exposure for Inuit who harvest and consume geese in Nunavik.

Foxes (Vulpes vulpes) as sentinels for parasitic zoonoses, Toxoplasma gondii and Trichinella nativa, in the northeastern Canadian Arctic

Outbreaks of Toxoplasma gondii and Trichinella spp. have been recurring for decades among Inuit of Nunavik, northeastern Canada. Contact with wildlife has been identified as a risk factor for Inuit exposure to T. gondii, but reservoirs have yet to be confirmed based on direct detection of DNA or organism. Similarly, little is known about the occurrence of Trichinella spp. in wildlife species of Nunavik other than walrus (Odobenus rosmarus) and bears (Ursus americanus, Ursus maritimus). Foxes (Vulpes vulpes) were targeted as possible sentinels for T. gondii and Trichinella spp. because of their high trophic position within the Arctic food chain as carnivorous scavengers. A total of 39 red foxes were sampled from four communities in southern and western Nunavik between November 2015 and September 2016. For the first time in wildlife, a novel magnetic capture DNA extraction and real-time PCR technique was used to isolate and detect T. gondii DNA from the heart and brain of foxes. A double separatory funnel digestion method followed by multiplex PCR was used to recover and genotype larvae of Trichinella spp. from tongues of foxes. Seroprevalence based on detection of antibodies to T. gondii was 41% (95% CI: 27-57%) using a commercially available modified agglutination test (MAT). Detection of DNA of T. gondii and larvae of Trichinella nativa (T2) occurred in 44% (95% CI: 28-60%) and 36% (95% CI: 21-51%) of foxes, respectively. Coinfection with both T. nativa and T. gondii occurred among 23% (95%CI: 13-38%) of foxes which can be attributed to co-transmission from prey and scavenged species in their diet. There was only moderate agreement between T. gondii serology and direct detection of T. gondii DNA using the MC-PCR technique (Kappa test statistic: 0.321), suggesting that using both methods in tandem can increase the sensitivity of detection for this parasite. These findings show that foxes are good sentinels for circulation of parasitic zoonoses in terrestrial northern ecosystems since they are highly exposed, show measurable indicators of infection and do not serve as exposure sources for humans.